44 FEESH-WATEE AQTJAEIA. 



Suitable rockwork can easily be constructed. It sbould be 

 of smaU dimensions rather than the reverse, as long as it will 

 answer its purpose ; for much rockwork takes up valuable space, 

 and does not look well in an aquarium. Care ought to be taken 

 to so aiTange it that, while it will afford the necessary shade to 

 the occupants of the tank, it will not at the same time provide 

 them with retreats into which they can retire altogether from 

 their owner's sight ; for, if the animals are able to completely 

 hide themselves, it is very possible that, should they die, their 

 deaths wUl be undiscovered until the corrupting bodies have 

 done irreparable damage to the whole aquarium. 



Rockwork may be made of pumice-stone, coke, melted glass, 

 mica-schist, or other material of a like kind. If the desired 

 shape and size cannot be found in one single piece, two or three 

 pieces may be joined together by means of Portland cement, 

 always remembering that this cement, after it has well set, 

 should be soaked for some days in water before it is placed in its 

 permanent position in the aquarium. Pieces of pumice-stone 

 or coke may be tmited by means of wooden rivets, each rivet 

 running into the adjoining parts a couple of inches, the holes 

 for which can easily be made with an ordinary awl. Before 

 coke is put in the tank it should be dipped into some liquid 

 Portland cement of about the consistency of ordinary whitewash, 

 keeping the mixture well stirred during the process. 



An aquarium like Fig. 9 may have rockwork so arranged 

 as to represent a cave, out of which and into which the fish 

 and other animals seem continually to go and come. To effect 

 this arrangement it will be necessary to get a piece of looking- 

 glass about 5in. square, more or less according to the size of 

 the tank. Paint the back of this two or three times with 

 sealing-wax varnish, japan black, or anything else which will 

 protect it from the action of the water ; then, when this is dry, 

 place the aquarium with the glass front upwards, and cover 

 its back, inside, with cement No. 2. Now take the looking-glass 

 and fix it firmly in the centre of the back of the tank, and 

 around it arrange mica-schist in such a way that the glass will 

 represent the mouth of a cave. All the back should be covered 

 with the stone. This plan, however, is more appropriate for 



